Peer to Peer Applications provide great scalability when the number of Clients increases. Presentation provides the overview of Peer to Peer application scalability

1. Peer to Peer Applications
Scalability
Rajkumar D

2. What is Peer to Peer Applications ?
 Client Server Applications -Most traditional applications are client server. Host
machine which sends the first request is generally the client and the machine
which is listening for the connection and responds to the request is the server.
For example HTTP browser requesting for a website is the client and the
server which responds to the request is the Server.
 Peer to Peer Application – Every host machine with Peer to Peer application
installed is both a server and a client. Depending on the ability of peer to
peer application it will open up new computing and bandwidth sharing across
different Peers.

3. Client Server Application
Bottleneck
serv er
1 Gbps
1 Mbps
1 Mbps
1 Mbps
With Increase in Clients PC’s , Server Link ( S bandwidth) becomes the bottleneck. If
there are N clients downloading file size of F. Then NF/S is the max speed

4. Peer to Peer Applications Scalability
serv er
1 Gbps
1 Mbps
1 Mbps
1 Mbps
With Peer to Peer Application each peer is both a server and Client. Hence with
increase in number of Clients Server link is not bottleneck . If there are N clients and
each client has the upload bandwidth of C. Then F/C is the max speed

5. Scalability of Peer to Peer Application – Client Server Model
Download Speed
Client Download Speed = D(I)
Server Upload Speed = U
Total Number of Systems Download at time t = N
Size of File to be downloaded = F
Transfer rate at Server Link = N * F /U
Access speed at Client = F/D(I)
Download rate will be max of (NF/U, F/D(I))

6. Scalability of Peer to Peer Applications – Peer to Peer model
Client Download Speed = D(I)
Server Upload Speed = U
Total Number of Systems Download at time t = N
Size of File to be downloaded = F
Total Upload Capacity = Upload capacity of all clients = Upload-time = U(1) + U(2)
+ U(3) + ….+ U(I)
Access speed at Client = F/D(I)
At the beginning only the server has the file so it will have to send the file to the
community at least once on the access link F/U(S)
Download rate will be max of (F/Upload-time, F/D(I), F/U(S))

7. Client Server and Peer to Peer Application download time
10
9
8
7
6
5
4
3
2
1
0
1 Mb file Download Times
1000 2000 3000 4000 5000 6000 7000 8000 9000
Time -Client server Time Peer -Peer
Above graph shows the Download time of client for a File size of 1 Mb and server side bandwidth
of 1 Gps and Client download speed of 1 Mbps. As number of clients increases download speed
goes up.
In the Client Server model as number of Clients accessing the file increases , Performance of the
Server goes down and download speed decreases for the clients.

8. Peer to Peer Applications - Example
 Popular Peer to Peer Applications are
 Bit Torrent
 Emule
 Gnutella
 Limewire
 KaZaA